Split tetrahedron with openings

ABSTRACT

A portable structure in the form of a regular tetrahedron having an opening in each of at least three sides thereof and comprising four side panels.

- United States Patent [1 1 Sajkovic 1 June 12, 1973 SPLIT TETRAHEDRON WITH OPENINGS [76] Inventor: Miriam Sajkovic, 101 College Street,

South Hadley, Mass. 01075 [22] Filed: Jan. 31,1972

[21] Appl. No.: 221,945

[52] 11.8. CI 35/72, 52/DIG. 10, 272/60 [51] Int. Cl A6311 33/04 [58] Field of Search 35/34, 60, 72;

46/21, 31; 272/60; 52/574, DIG. 10

[56] References Cited 7 UNITED STATES PATENTS 2,216,915 10/1940 Johnson 35/72 UX 1,479,147 1/1924 Markworth 35/72 3,472,509 10/1969 Flynn 272/60 3,666,266 5/1972 Noguchi 272/60 Primary Examiner-Harland S. Skogquist AttorneyJames B. Lampert [57] ABSTRACT A portable structure in the form of a regular tetrahedron having an opening in each of at least three sides thereof and comprising four side panels.

10 Claims, 4 Drawing Figures SPLIT TETRAI-IEDRON WITH OPENINGS This invention relates to portable structures.

It is a principal object of the present invention to provide a portable structure, especially suitable for use as a childs playhouse or in a learning environment, which is always right-side-up and which in any position will provide both security (privacy) and a wide range of vision (through at least two openings). Other objects include providing such a structure which is safe, quiet, light-weight, of such simple construction that it can be erected by a child, and completely regular.

The invention features a portable structure in the form of a tetrahedron having an opening in each of at least three of the sides thereof and comprising four side panels, each side panel having a major base and a pair of non-parallel sides, at least three of the side panels being in the shape of a trapezoidum, respective pairs of the side panels being connected along the major bases thereof and the connected major bases defining two edges of the tetrahedron, each of the openings being defined by a minor base of a side panel of one of the pairs and a side of each of the side panels of the other of the pairs, and the pairs being connected to each other. In preferred embodiments in which the tetrahedron is regular and the structure has an opening in each side thereof, there is featured each side panel in the shape of a isosceles trapezoid whose sides and minor bases are of equal length, and each pair comprising a pair of panels hingedly connected together and having the shape of a regular hexagon.

Other objects, features, and advantages will appear from the following detailed description of a preferred embodiment of the invention, taken in conjunction with the attached drawings in which:

FIG. I is a perspective view of a structure embodying the present invention;

FIG. 2 is an exploded perspective view of the structure of FIG. 1;

FIG. 3 is a perspective view, partially in section, of a portion of the structure of FIG. 1; and

FIG. 4 is a plan view of a component useful in construction of structures such as that of FIG. 1.

Referring more particularly to the drawings, there is shown in FIGS. 1-3, a portable structure, generally designated 110, in the shape of a tetrahedron and including a triangular opening 12 extending through each of the sides, 14, 16, 18, 20, thereof. As shown, structure is constructed of a pair of identical, hexagonallyshaped pieces 22, 24 of corrugated paperboard, Each piece is folded along a fold line 26 extending between a pair of apexes of its hexagonal periphery into two identical side panels, each of which provides one side of the structure. As shown, piece 22 forms side panels 28, 30 providing sides 16, 14; piece 24 forms side panels 32, 34 providing sides 18, 20.

All side panels are identical and each has the shape of an isosceles trapezoid whose major base is defined by a fold line 26 and whose minor base 36 and sides 38 are defined by respective edges of pieces 22, 24.

For securing pieces 22, 24 together, a pair of drilled holes 40 are provided in each side panel 28, 30, 32, 34,

other piece. A connecting block 44 is placed within the structure 10 adjacent each pair of engaged corners, and bolts 46 extend through each hole 40 into and through a block 44.

Each opening 12 of structure 10 is defined by a minor base 36 of a side panel of one of pieces 22, 24 and two edges 38 of side panels of the other of pieces 22, 24. The length of each side of each opening 12, and also of each minor base 36 and side 38 of each side panel, is equal to one-half the length of an edge of the tetrahedron formed by the structure.

Reference is now made to FIG. 4 wherein is illustrated a unit, generally designated 50, used in the construction of a heavy duty structure similar to structure 10. As shown, unit 50 comprises a pair of plywood panels 52, 54 connected to each other by 2 hinges 56. Each of panels 52, 54 is identical in size and shape to one of side panels 28, 30, 32, 34, including drilled openings 58 corresponding to openings 40. In constructing the heavy duty structure, one unit 50 is simply substituted for each of pieces 22, 24 of structure 10.

For various desired uses, portable structures according to the present invention may be constructed of relatively lightweight materials other than cardboard or corrugated paperboard. One such other material that has been found to be especially useful is foam sheeting. A foam structure can be jumped on, rolled in, or fallen on. It offers little or no resistance and will only collapse, absorbing any impact and protecting the child. Once pressure is removed, a foam structure will bounce back to once again maintain its original shape. Like structures of strong cardboard, a foam house has no sharp edges. Such foam or other lightweight structures, may either comprise two pieces (each having the same size and shape of pieces 22, 24) folded about a center fold line, or four pieces (each having the same size and shape as one of pieces 52, 54) hingedly connected. In many lightweight structures connecting blocks and bolts may be omitted and the pieces interconnected to form a tetrahedron structure by means of mating slits or slots provided in the respective adjacent comer portions of the various side panels.

Other embodiments within the scope of the following claims will occur to those skilled in the art.

What is claimed is:

I. A portable structure in the form of a tetrahedron having an opening in each of at least three of the sides thereof and comprising four side panels,

each of said panels having a major base and a pair of non-parallel sides extending from said major base thereof,

at least three of said side panels being in the shape of a trapezoidum and having a minor base spaced from said major base thereof,

respective pairs of said side panels being connected along said major bases thereof and said connected major bases of said pairs defining two edges of said tetrahedron,

each of said openings being defined by a minor base of one of said panels of one of said pairs and a side of each of said side panels of the other of said pairs, and

said pairs being connected to each other.

2. The structure of claim 1 wherein each of said side panels is in the shape of a trapezoid and said structure includes an opening in each side thereof.

3. The structure of claim 1 wherein each of said trapezoidums is an isosceles trapezoid and said tetrahedron is a regular tetrahedron.

4. The structure of claim 1 wherein each of said pairs comprises a unitary member folded along a fold line, said fold line defining said major bases of said panels of saideach pair.

5. The structure of claim 1 wherein each of said pairs comprises a pair of members hingedly connected to each other along said major bases thereof.

6. The structure of claim 3 wherein the length of each of said sides of each of said isosceles trapezoids is equal to the length of said minor base of said each trapezoid.

7. The structure of claim 6 wherein said structure includes an opening on each side thereof.

8. The structure of claim 7 wherein each of said pairs has the shape of a regular hexagon.

9. The structure of claim 8 including a plurality of connectors detachably connecting said pairs, each of said connectors engaging a portion of one of said pan- 

1. A portable structure in the form of a tetrahedron having an opening in each of at least three of the sides thereof and comprising four side panels, each of said panels having a major base and a pair of nonparallel sides extending from said major base thereof, at least three of said side panels being in the shape of a trapezoidum and having a minor base spaced from said major base thereof, respective pairs of said side panels being connected along said major bases thereof and said connected major bases of said pairs defining two edges of said tetrahedron, each of said openings being defined by a minor base of one of said panels of one of said pairs and a side of each of said side panels of the other of said pairs, and said pairs being connected to each other.
 2. The structure of claim 1 wherein each of said side panels is in the shape of a trapezoid and said structure includes an opening in each side thereof.
 3. The structure of claim 1 wherein each of said trapezoidums is an isosceles trapezoid and said tetrahedron is a regular tetrahedron.
 4. The structure of claim 1 wherein each of said pairs comprises a unitary member folded along a fold line, said fold line defining said major bases of said panels of said each pair.
 5. The structure of claim 1 wherein each of said pairs comprises a pair of members hingedly connected to each other along said major bases thereof.
 6. The structure of claim 3 wherein the length of each of said sides of each of said isosceles trapezoids is equal to the length of said minor base of said each trapezoid.
 7. The sTructure of claim 6 wherein said structure includes an opening on each side thereof.
 8. The structure of claim 7 wherein each of said pairs has the shape of a regular hexagon.
 9. The structure of claim 8 including a plurality of connectors detachably connecting said pairs, each of said connectors engaging a portion of one of said panels of one of said pairs adjacent a corner thereof defined by a side and said minor base thereof and a portion of one of said panels of the other of said pairs adjacent a corner thereof defined by a said side and said minor base thereof.
 10. The structure of claim 8 wherein each of said pairs comprises a unitary member of one of paperboard and foam rubber folded along a fold line, said fold line defining said major bases of said panels of said each pair. 